在 MySQL 准备语句中使用表名设置用户定义变量?
mysqlmysqli database
首先我们创建一个表 −
mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(20) ); Query OK, 0 rows affected (0.71 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable(StudentName) values('Chris');
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable(StudentName) values('David');
Query OK, 1 row affected (0.06 sec)
mysql> insert into DemoTable(StudentName) values('Sam');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(StudentName) values('Mike');
Query OK, 1 row affected (0.12 sec)
使用 select 语句显示表中的所有记录 −
mysql> select * from DemoTable;
这将产生以下输出 −
+-----------+-------------+ | StudentId | StudentName | +-----------+-------------+ | 1 | Chris | | 2 | David | | 3 | Sam | | 4 | Mike | +-----------+-------------+ 4 rows in set (0.00 sec)
以下是如何使用用户定义变量来设置表名并与 MySQL 准备语句一起使用 −
mysql> set @tableName = 'DemoTable';
Query OK, 0 rows affected (0.04 sec)
mysql> set @queryToSelectStudentName := concat('select StudentName from ',@tableName);
Query OK, 0 rows affected (0.28 sec)
mysql> prepare executeQuery from @queryToSelectStudentName;
Query OK, 0 rows affected (0.04 sec)
Statement prepared
mysql> execute executeQuery;
这将产生以下输出 −
+-------------+ | StudentName | +-------------+ | Chris | | David | | Sam | | Mike | +-------------+ 4 rows in set (0.00 sec)
